POTENTIAL DISPERSAL OF DAPHNIA LUMHOLTZI FROM WILLARD BAY TO OTHER BODIES OF WATER IN UTAH AND SOUTHERN IDAHO VIA BOATS AND/OR BIRDS.

Daphnia lumholtzi, native to Australia, Africa, and Southern Asia, was observed in Willard Bay, Utah in the autumn of 1999. This represents the first report of Daphnia lumholtzi in the intermountain West. It is probable that this foreign invader has, or will spread from Willard Bay to other bodies of water in Utah and Southern Idaho. Thousands of recreational boaters use Willard Bay and subsequently launch into other reservoirs and lakes. Daphnia lumholtzi could rapidly be dispersed via Willard Bay water that remains in the bilge systems of these boats. Also, waterfowl that migrate from Willard Bay to other bodies of water may disperse resting eggs of Daphnia lumholtzi. To determine if Daphnia lumholtzi was dispersing from Willard Bay, zooplankton were collected from twelve bodies of water in Utah and Southern Idaho in September 2001. Daphnia lumholtzi was absent in all of the samples. However, Daphnia lumholtzi resting eggs are probably present in some of the sites. Therefore, a monitoring study will be initiated to determine if Daphnia lumholtzi is establishing viable populations throughout Utah and Southern Idaho.